Performance and reliability improvements in poly-Si TFT's by fluorine implantation into gate poly-Si

Maegawa, Satoru; Ippóshi, T.; Maeda, S.; Nishimura, Hiromichí; Ichiki, T.; Ashida, M.; Tanina, O.; Inoue, Yasuo; Nishimura, Tadashi; Tsubouchi, N.

doi:10.1109/16.387244

Cited by 27 publications

(18 citation statements)

References 8 publications

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“…We deduce that for the control TFT, there exists lots of dangling bonds and strain bonds near the SiO /poly-Si interface, resulting in high deep states and tail states [13]. On the contrary, for the CF plasma treated TFT, fluorine atoms were introduced into the SiO /poly-Si network to terminate the dangling bonds, release the strain bonds and form the S-F bonds, improving the device characteristics [5].…”

Section: Resultsmentioning

confidence: 98%

A novel process-compatible fluorination technique with electrical characteristic improvements of poly-Si TFTs

Wang

Chang

et al. 2005

IEEE Electron Device Lett.

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A process-compatible fluorine passivation technique of poly-Si thin-film transistors (TFTs) was demonstrated by employing a novel CF 4 plasma treatment. Introducing fluorine atoms into poly-Si films can effectively passivate the trap states near the SiO 2 /poly-Si interface. With fluorine incorporation, the electrical characteristics of poly-Si TFTs can be significantly improved including a steeper subthreshold slope, smaller threshold voltage, lower leakage current, higher field-effect mobility, and better On/Off current ratio. Furthermore, the CF 4 plasma treatment also improves the reliability of poly-Si TFTs with respect to hot-carrier stress, which is due to the formation of strong Si-F bonds.

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Section: Resultsmentioning

confidence: 98%

A novel process-compatible fluorination technique with electrical characteristic improvements of poly-Si TFTs

Wang

Chang

et al. 2005

IEEE Electron Device Lett.

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“…27) The bulk trap was caused by breaking the Si-O bond and poorer quality in the bulk gate oxide because of relaxation of the strain Si-O-Si when fluorine was implanted in the poly gate. [28][29][30][31] After NBTI stress, the noise level of W/O F I/I increased while there is little change of slope after stress as in Fig. 8…”

Section: Resultsmentioning

confidence: 99%

Effect of fluorine implantation on recovery characteristics of p-channel MOSFET after negative bias temperature instability stress

Kwon

et al. 2014

Jpn. J. Appl. Phys.

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In this paper, the effect of fluorine implantation on the recovery characteristics of p-channel MOSFETs (PMOSFETs) after negative bias temperature instability (NBTI) stress was investigated. PMOSFETs using fluorine ion implantation (F-I/I) performed better than those without F-I/I after NBTI stress; it is thought that F-I/I can suppress the generation of permanent damage during NBTI stress. The relationship of ΔV th and ΔSS during NBTI stress and recovery showed how much permanent damage occurred. In addition, we confirmed with a 1/f noise measurement that the device with F-I/I was immune to NBTI stress in spite of a pre-existing bulk trap caused by implantation damage. Moreover, the device with F-I/I had greater activation energy than the device without F-I/I. As indicated by the results, fluorine implantation can decrease the generation of permanent damage under NBTI stress because of the stable Si-F bond.

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“…To reduce the density of the trap state, a fluorine implantation technology was commonly used in silicon wafer. Since the fluorine has a strong electronegativity, it breaks the weak deformed silicon bonds and forms the strong Si-F bonds [10][11][12]. These fluorine bonds were known to be very effective in reducing the trap state density and passivating the unsaturated bonds [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

“…Since the fluorine has a strong electronegativity, it breaks the weak deformed silicon bonds and forms the strong Si-F bonds [10][11][12]. These fluorine bonds were known to be very effective in reducing the trap state density and passivating the unsaturated bonds [10][11][12]. Ha et al [13] reported that the dark current properties could be improved as a result of selective application of the fluorine implantation to the NMOS transistor of a CMOS image sensor.…”

Section: Introductionmentioning

confidence: 99%

Reduction of Fluorine Diffusion and Improvement of Dark Current Using Carbon Implantation in CMOS Image Sensor

Chai

Choa

2021

Crystals

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Recently, the demand of a high resolution complementary metal-oxide semiconductor (CMOS) image sensor is dramatically increasing. As the pixel size reduces to submicron, however, the quality of the sensor image decreases. In particular, the dark current can act as a large noise source resulting in reduction of the quality of the sensor image. Fluorine ion implantation was commonly used to improve the dark current by reducing the trap state density. However, the implanted fluorine diffused to the outside of the silicon surface and disappeared after annealing process. In this paper, we analyzed the effects of carbon implantation on the fluorine diffusion and the dark current characteristics of the CMOS image sensor. As the carbon was implanted with dose of 5.0 × 1014 and 1 × 1015 ions/cm2 in N+ area of FD region, the retained dose of fluorine was improved by more than 131% and 242%, respectively than no carbon implantation indicating that the higher concentration of the carbon implantation, the higher the retained dose of fluorine after annealing. As the retained fluorine concentration increased, the minority carriers of electrons or holes decreased by more Si-F bond formation, resulting in increasing the sheet resistance. When carbon was implanted with 1.0 × 1015 ions/cm2, the defective pixel, dark current, transient noise, and flicker were much improved by 25%, 9.4%, 1%, and 28%, respectively compared to no carbon implantation. Therefore, the diffusion of fluorine after annealing could be improved by the carbon implantation leading to improvement of the dark current characteristics.

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Performance and reliability improvements in poly-Si TFT's by fluorine implantation into gate poly-Si

Cited by 27 publications

References 8 publications

A novel process-compatible fluorination technique with electrical characteristic improvements of poly-Si TFTs

A novel process-compatible fluorination technique with electrical characteristic improvements of poly-Si TFTs

Effect of fluorine implantation on recovery characteristics of p-channel MOSFET after negative bias temperature instability stress

Reduction of Fluorine Diffusion and Improvement of Dark Current Using Carbon Implantation in CMOS Image Sensor

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